Providing seamless services is a critical issue for the success of wireless networks. In the context of services supported by the Internet protocol (IP), seamless IP-layer connectivity is necessary as a mobile terminal undergoes a handoff to a new access router with minimal disruption to the mobile terminal's Internet connectivity. There are several approaches to providing such seamless IP connectivity. First, the mobile IP protocol describes a mechanism that allows packets to be routed through the Internet to a new access router when the mobile terminal changes its point of attachment to the Internet from a current access router to a new access router. Also, after having established link-layer connectivity with the new access router, the mobile terminal typically engages in signaling the new access router in order to obtain its new care-of-address. When obtaining the new care-of-address, the mobile terminal has acquired IP-level connectivity with the new access router so that the mobile terminal can transmit and receive packets with the new access router. A fast handoff protocol enables forming the new care-of-address while the mobile terminal is still attached to the current access router. As soon as the mobile terminal acquires link-layer connectivity with the new access router, the mobile terminal can transmit and receive packets with the new access router.
Moving the mobile terminal's point of attachment to the Internet from the current access router to the new access router may not suffice to provide seamless service if the mobile terminal's application requires additional features for packet transport such as transport quality of service (QoS), security, and header compression. These features need to be provided at the new point of mobile terminal's attachment to the Internet after IP-layer handoff. This can be achieved via context transfer framework. Current approaches to a context transfer framework limit solutions to seamless IP-layer connectivity and do not address the service and business related aspects. In other words, ability to exchange packets with the Internet in an uninterrupted fashion in the light of handoffs as considered by current approaches, does not necessarily mean that the multimedia application on the mobile terminal will continue seamlessly. This is because, applications may make use of certain application-specific network functionalities, which may need to be relocated or provisioned concurrently with IP-layer handoffs.
Having the same content source support the mobile terminal after the IP-level handoff as before the IP-level handoff may present a number of issues. For example, the administrator of the network domain before the handoff may not be allowed to provide media content in the network domain after the handoff for several reasons. First, copyright restrictions based on the geographical location of the mobile terminal may restrict a region that a content source can serve. Also, a service provider may not allow the copyrighted and paid for content to cross its administrative network boundaries so as to prevent illegal copying and distribution of the content by third parties. Second, business agreements, such as revenue sharing between different wireless service providers and different content providers, may place limits on the span of a content source. Third, because of a number of mobile terminals that a content source can serve and a non-uniform traffic pattern that is served by a wireless system, the content source may be limited in the geographical region that the content source can serve. Moreover, it may not be economical to transport the media content from the content source to the new access network that is connected to the new access router, as they can be at large logical distances (such as in terms of IP hops) from each other.
Mobile applications, such as multimedia mobile Internet applications, typically require more than IP-connectivity to the Internet in order to provide seamless service for a mobile terminal. Even though a mobile terminal is able to exchange packets with the network, the mobile terminal may not be able to immediately execute an Internet application upon the completion of the handoff. Consequently, service disruption may occur despite having seamless IP connectivity if the application-specific functionality is not relocated at the time of mobile terminal's IP-level handoff.
Appropriate mechanisms may be required to relocate the content source from the current content source in the network domain before an IP-level handoff to the new content source in the network domain after the handoff so that the corresponding application executes seamlessly for the mobile terminal.